LONDON — REPRESENTATIVES of 61 nations have signed an agreement designed to strengthen the drive to protect the ozone layer, which shield's the earth's atmosphere from ultraviolet radiation. But critics of the timetable approved here Friday say the program is too little and takes too long. The deal was reached after 12 days of tough negotiations by ministers and officials from 92 countries - several of them observers. Their goal was to strengthen the Montreal Protocol, the 1987 international treaty on the protection of the ozone layer.
The conferees agreed to phase out chlorofluorocarbons - better known as CFCs - by the year 2000, and to speed up the development of safer substitutes. For the first time, a limit was also set on the use of two other ozone-depleting gases - methyl chloroform and carbon tetrachloride. Halons - gases used in firefighting - will also have to go in 10 years' time, except where they are irreplaceable.
Representatives of 13 countries, not convinced that the timetable was swift enough, signed a separate declaration of their ``firm determination to take all appropriate measures to phase out the production and consumption of all CFCs ... not later than 1997.''
Even that is not soon enough for Joe Farman, the British scientist who discovered the hole in the ozone layer. Mr. Farman, head of atmospheric dynamics at the British Antarctic Survey, called the agreement ``very disappointing'' and said it failed to address some of the key environmental issues at stake.
Mr. Farman said the target dates for phasing out ozone damaging CFCs were too distant, that insufficient attention had been paid to the dangers posed by alternatives, and that the importance of recycling the chemicals to prevent their release into the atmosphere had been overlooked.
The environmental groups Greenpeace and Friends of the Earth criticized the agreement for not going far enough.
A 15-nation committee was set up to distribute a fund tentatively set at $240 million to assist developing countries in using alternatives to CFCs, chemicals which are used as aerosols, refrigerants and foams. Scientists believe the substances are gradually destroying belts of ozone which sit about 20 miles above the earth and block out ultraviolet rays.
One major step forward was the agreement of China and India to join the treaty. But officials of the two nations refused to sign until they were assured that other countries would not try to restrict access to new technology through trade barriers and patent laws.
Indian Environmental Minister Naneka Gandhi said she had secured an escape clause which would exempt nations from participating if they could not gain access to the proper technology. ``You must help us with knowledge.'' she said. ``You can't just give us a small sum of money and say that's it. We are not beggars.''
The agreement of China and India was considered vital to the success of the meeting, as they account for 40 percent of the world's population.